The invention relates to a preparation method for 
bismuth silicate powder photocatalyst. At first pentahydrate 
bismuth nitrate and 
active agent on the surface of a segmented 
copolymer are dissolved in 
acetic acid to form uniform clear solution, and then 
silicate ester is added into solution containing 
bismuth according that the mol ratio of bismuth to 
silicon is equal to 12:1, and is fully mixed to form uniform 
sol. After aging, the solution is moved into an 
autoclave to be hermetically crystallized, so as to obtain the 
composite oxide gel of the bismuth and the 
silicon, and after being filtered, cleaned, and dried, at last precursor 
powder is roasted in the air environment, namely, the bismuth 
silicate powder photocatalyst of the 
granularity with 
micron size is obtained. The invention can stably and uniformly obtain the bismuth silicate powder with good 
crystallinity under the lower temperature, and the 
granularity of the photocatalyst is larger, thereby being convenient for being separated from a 
water body to facilitate the 
recovery and the operation, the photocatalyst has highly effective photocatalytic activity, and is applicable for photocatalytic degrading organic pollutants.